Firearm accessories are often installed on a firearm using an accessory rail, such as a “Weaver” or “Picatinny” rail, and a separate or integral mount is used to couple the accessory to the rail. FIG. 1 shows an example of a scope 11 mounted on rail 13 of firearm 15 with separate ring mounts 17, 19, whereas FIG. 2 shows a sight 21 mounted on rail 23 of firearm 25 with an integral mount 27.
FIG. 3 shows a portion of a typical accessory rail 29, which has slots 31 that extend laterally across rail 29 and define lugs 33. This full-lug configuration is also shown on rails 13, 23, though other styles of rails have only partial lugs on the lateral portions of the rail. Each slot 31 is defined by a depth from top lug surface 35 and a width between lugs 31, a bottom slot surface 37 extending across the full width of rail 29. Opposing pairs of angled clamping flats 39, 41 and 43, 45 are located on the lateral edges of rail 29, with continuous bottom flats 41, 45 and upper flats 39, 43 interrupted by slots 31.
FIG. 4 shows a typical two-piece mount configuration, with mount 47 comprising body 49 and clamp 51. Threaded nuts 53 are coupled to shafts 55, which extend across the width of body 49, and nuts 53 may be rotated relative to shafts 55 to apply compressive force against clamp 51. FIG. 5 shows mount 47 mounted on rail 29 (shown in phantom), with opposing pairs of flats 57, 59 and 61, 63 adjacent corresponding pairs of flats 39, 41 and 43, 45 on rail 29. Rotating nuts 53 pulls body 49 and clamp 51 together, clamping mount 47 on rail 29. Shafts 55 protrude below top lug surface 35 and into slots 31, allowing shafts 55 to limit the longitudinal motion of mount 47 on rail 29 by contacting a lug 33. Due to the opposing forces of rearward recoil of the firearm and inertia of the mount (and accessory), mount 47 is typically pushed forward during installation until one or more shafts 55 contacts a forward lug 33. In addition or alternatively, body 49 may have integral recoil lugs depending from body 49 and into slots 31.
FIG. 6 shows a one-piece mount configuration on a riser 65, which is used to space an accessory from an accessory rail. Riser 65 comprises a rail section 67 and a clamp section 69, with rail section 67 having a configuration of slots and lugs as described above for rail 29. Because riser 65 is one-piece, riser 65 is installed by removing fasteners 71 and sliding riser 65 longitudinally along an accessory rail to a desired position, and then fasteners 71 are reinstalled. Fasteners 71 extend through slots in the accessory rail, providing the same locating function as shafts 55 for mount 47 of FIGS. 4 and 5. Like mount 47, clamp section 69 has opposing pairs of flats for engaging the flats of the accessory rail, and fasteners 71 pull the lateral portions of clamp section 69 toward each other to provide a clamping force on the accessory rail.
While the apparatus of this patent application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the application to the particular embodiments disclosed, but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this application as defined by the appended claims.